Investigations will be continued on the mechanism of action of ethanolamine ammonia-lyase, a B12-dependent enzyme. Analogs of the substrate will be tested for their effect on the enzyme-coenzyme complex. The interaction between enzyme and w-adenylalkyl cobalamins will be studied to test the hypothesis that the enzyme facilitates the rupture of the coenzyme at the carbon-cobalt bond by stretching the bond. The stereochemistry of the rearrangement will be investigated using stereospecifically labelled ethanolamine and propanolamine as substrate. Finally, studies will be initiated to test the hypothesis that transalkylation of the cobalt participates in the catalytic process.